The present invention relates to a device for controlling inductive loads, in particular of injectors of an internal combustion engine injection system.
As is known, to control the injectors of an internal combustion engine injection system, each injector must be supplied with current, the curve of which comprises a rapidly increasing portion, a more slowly increasing portion, a portion decreasing to a hold value, a portion oscillating about the hold value, and a portion decreasing to zero.
To achieve such a curve, control devices are currently employed whereby the inductive loads of the injectors are connected on one side to a low-voltage supply source, and on the other side to a ground line via a controlled electronic switch. A major drawback of control devices of this sort is that, in the event of ground shorting of one of the terminals of any one of the inductive loads--e.g. due to impaired insulation of of an injector conductor, and contact between the conductor and the vehicle body--the injector and/or control device is irreparably damaged and the engine is turned off--an extremely dangerous situation when the vehicle is moving.
To eliminate the above hazard, control devices have been proposed whereby the inductive loads of the injectors are grounded on one side and connected on the other side to an internal node of the control device itself, so that, as opposed to damaging the control device and turning off the engine, ground shorting of one of the terminals of the inductive loads simply results in that particular injector being put out of use, so that the vehicle continues running minus one injector.
Such control devices, however, in addition to involving complex, high-cost circuitry, normally fail to provide for simultaneously injecting different cylinders, as required for example by engine injection systems involving multiple injection of each cylinder.